1. Field of the Invention
The present invention relates to soil fracture, soil excavation and soil treatment using supersonic nozzles, in particular to a method and apparatus for soil excavation and treatment using supersonic pneumatic nozzle with integral fluidized material injector for incorporating liquids or fluidized pellets into the air stream.
2. Background Information
Tools for digging safely in the earth to either uncover buried objects or to dig safely near them using compressed air as an energy source and as a digging medium have been used in recent years. U.S. Pat. No. 5,782,414, which is incorporated herein by reference, exemplifies that it has been well known that compressed air released in close proximity to and directed toward the ground can result in loosening of a number of types of soil. A number of tools have been marketed produce an air stream for improved digging purposes by making the air exit the tool at a supersonic speed. For example, U.S. Pat. No. 4,813,611, which is incorporated herein by reference, discloses a compressed air nozzle for use in soil excavation to uncover buried pipes, electrical cables and the like. U.S. Pat. No. 5,170,943 discloses a similar tool with a handle, valve, electrically insulating barrel, and a nozzle. The '943 patent includes a conical shield to protect the operator, but nothing to protect the nozzle. U.S. Pat. No. 5,212,891 discloses a further excavating pneumatic nozzle design.
A wand or tool, consisting of a valve, length of pipe or tubing, and ending in a reduced sized nipple or nozzle, supplied with air from a standard portable compressor, is commonly used for the purposes of dislodging soil safely from around underground utilities such as gas, water, or sewer pipes and electric, telephone, television, or other cables. The compressed air does not pose a hazard of damaging the buried utility as does a pick, digging bar, spade, bucket, or blade.
The ability to unearth safely other types of buried objects is also important. For example, in the industrial or nuclear energy sectors, such objects include glass bottles, cardboard or wood boxes, metal or fiber drums, or metal cylinders of chemical or radioactive waste. From the military sector, objects include all types of unexploded ordnance or chemical munitions.
These tools have also been used to disturb and fracture soil structure for the purpose of reducing compaction (de-compaction) and other arboriculture purposes. One purpose of this fracturing is to facilitate the propagation and growth of plant roots, which otherwise can not grow into significantly compacted soil. This difficulty for plants is further aggravated, when compacted soil has a low moisture content. Another purpose of this fracturing, which tends to occur laterally from a vertical hole opened by a supersonic nozzle's jet stream, as an example, has been used to insert soil remediation materials beneficial to plants, either liquid or solids. This procedure has also been used, for other various purposes, including the amelioration of the hazardous properties of soil contaminants.
As a matter of clarification, air excavation nozzles should not be confused with the rocket nozzles. Supersonic air excavation nozzles used for excavation purposes are different than rocket nozzles in a number of important ways. Supersonic air nozzles for earth excavation operate at significantly lower pressures and temperatures than rocket nozzles. For example, a rocket's chamber pressure may reach 1,000 to 3,000 psig and the exhaust gas temperature may be 1,800° to 7,700° F., while typical gas jet excavation nozzles operate at around 100 to 200 psig and at 80° to 140° F. The velocity of the exhaust gas exiting from a chemical rocket's nozzle may be from 6,000 to 14,000 ft/sec; while for an excavation nozzle typical values are from 1,700 to 2,000 ft/sec. The specific nozzle profile for a typical rocket nozzle is, thus, significantly different in shape than for an air excavation nozzle.
U.S. Pat. No. 6,845,587 describes the practices of revival woody plants that are in decline, which revival of the plant is usually preferred to replanting. Revival avoids costs for removal and additional costs for replacement. Typically, revival has meant either aggressively fertilizing the subject plant and/or loosening the soil. Revival success is dependent on the degree of soil compaction and existing moisture content. Earlier methods include laboriously exposing roots using trowels and small digging implements. Once exposed, the roots were reburied with new loose soil or covered with the existing soil now more loosened. This early, labor intensive method is similar to the way archaeologists dig for shards of pottery—slow and tedious. An improvement over manual excavation is a vertical mulching technique where a grid of 1 to 2 inch holes is drilled in the rooting soil. The holes are then backfilled with porous material and/or fertilizer.
One technique of soil loosening uses compressed air. Compressed air released at supersonic speed fractures the soil, with minimal damage to roots. Unlike porous soil, non-porous matter, such as roots, remain minimally damaged by the compressed air. Soil fracturing avoids the problems of mechanical excavation.
Fracturing soil by using compressed air is popularly used on lawns and turfs, such as golf courses. To maximize efficiency compressed air is injected in a grid. The grid is spaced so to aerate the soil evenly throughout a specified area by fracturing the soil.
Specifically, U.S. Pat. No. 6,845,587 provides for the provision of a method of improving the rooting soil of a woody landscape plant comprising the steps of exposing a root collar of a plant; defining a first improvement zone encompassing the root plate area; excavating the first improvement zone with an air excavator; and adding a beneficial treatment to the first improvement zone.
In a related field, soil treatment is often required in many applications, such as for plant treatment or soil remediation applications. Tools for injecting liquids and solids (such as granular pellets) into the ground are in use and which utilize a wide variety of injection methods, including manually by hand, pumps, and mechanical augers. These systems are often unsatisfactory because of their inefficiencies (manual & inductors) and potential for mechanical damage to roots and buried utilities (e.g., augers).
One purpose of this invention is to provide an improved, efficient, integrated, safe, light weight, optimized and economical combination of supersonic air digging and high velocity liquid or fluidized material (e.g., pellets) induction directly into the supersonic air stream, for many purposes, including those enumerated above, using a single source of compressed air.